Sanding drum



April 15, 1947- T. L. BONKOWSKI SANDING DRUM Filed Nov. 25, 1944 2 Sheets-She9i l INVENTOR. BY 720;. L. BONKOWSKI AGENT.

April 15, 1947. I T. L. BONKOWSKI 2,413,966

Y SANDING DRUM Filed Nov. 23, 1944 v 2 Sheets-Sheei 2 R :0 MN mm m M w m mi fl v2 I E L 2 2 L m B m RXUW 2 E Z M 4 A T Z 6 2 V 5 2 .6 6 I Y K B a m f 5 W w v Patented Apr. 15, 1947 UNITED STATES PATENT OFFICE 2,418,966 SANDING DRUM Teofil L. Bonkowski, Los Angeles, Calif.

Application November 23, 1944, Serial No. 564,799

7 Claims.

This invention relates to drums for sanding or surface-finishing wooden, plastic, metal or other articles having irregular surfaces wherein parts thereof are recessed and too narrow for accessibility thereto with conventional sanding means.

Like other known types of drums for the use stated, some of them functioning with more or less success, this invention too utilizes a plurality of sanding strips collectively wound on a single core and a corresponding pluralityof backing elements for resiliently supporting the free or Working ends of the sanding strips respectively.

This invention is however distinguished from known similar devices in that it embodies a provision for the facile, quick presentation and with drawal of the free ends of the strips without opening the drum, which is occasioned only by the need to replace-a cartridge of consumed sanding strips or to replace the backing elements when they too are worn out.

A further advantageous provision is the ability to readily and quickly replace the backing elements and the cartridge, together with the simultaneous replacement of a set of sanding strips,

which is rendered possible by the unusually simple, neat and efiicient means for retention thereof.

Additional objects of and advantages in this invention are that a drum embodying it lends itself to economy with respect to use and maintenanoe as well as to manufacturing thereof and provides more consistently good performance and freedom from breakdown.

Further objects and advantages disclose themselves in the hereincontained description of a typical drum embodying the invention, aided by the accompanying drawings, in which- Figure 1 is a schematic elevation view of a drum embodying my invention, with a certain cover plate, spider and nut removed from the view.

Figure 2 isa schematic plan view of the same.

Figure 3 is an exploded, isometric, half-sectional view of all parts of the drum but without the sanding strips and backing elements being present.

Figure 4 is a quarter-cross-sectional view of all parts of a certain reel, as seen in the plane 4-4 in Figure 3, modified by the presence of fragmentarily illustrated sanding strips.

As employed herein, the mount or carrier for the strips is referred to as the reel, the expression, cartridge, being reserved for the combination of the reel and the thereon wound abrasive or sanding strips. M

',I'1 1e expression, strips, in the plural, shall be understood to refer to a plurality of sanding strips spaced from one another. When used in the singular, it shall be understood to refer to a non-slit strip or to one that has been slit entirely thruout the length thereof in order to constitute, as is preferred and usual in sanding drums of this class, a plurality of successively edgewise adjoining narrow strips that do not overlie one another, or to one that has been slit for the greater part thereof, leaving a relatively short, unslit inside or retained end as a con venient anchor for the entire strip at the cartridge, to which the strip is secured by said short end.

The term, sandpaper, and all other terms related to or deriving therefrom, shall not be interpreted narrowly as an abrading strip whose base is of paper but broadly to include abrading strips of all kinds regardless of whether the base thereof is of paper, or cloth or otherwise.

Referring to the drawings, the basic structural member of the drum is indicated by ill. It includes the mutually integral supporting plate l2, hub I3, also referred to as a connecting means, spindle I4 and channel-like housing l5, also referred to as mounting means. The hub is provided with the axial recess 25. Not shown, but readily envisaged, is a power-rotated shaft, whose axis is indicated by A, and to which shaft the plate I2 is securingly engaged thru the medium of said hub, in which threaded holes l6 can be seen for accommodating a pair of setscrews. Axis A is also the axis of the hub and the spindle. The shaft end is received by axial recess 25 and retained therein by said setscrews. The drum is mounted on the shaft of course symmetrically. Although the figures show a drum of conventional, transversely circular form,- it may take a transversely octagonal or otherform, because it is only the sanding strips and the backing elements that are in contact with the Work. I

A cover. plate l1, provided with a flange l IA and a cover opening l8, that is substantially alined with axis A, engages the shouldered free edges of wall-sections l9, which edges engage flange A. Cover opening I8 has a diameter appreciably larger than that of the spindle, in fact, large enough to receive therethru, as will be referred to below, an extension of the reel. Plates l2 and I9 are disposed respectively in two planes substantially rectangular to axis A and defining, between them, the interior of the drum,

which is additionally defined by housings I5 and wall-sections I 9. The spindle I4 extends from the strip-confronting or inside surface of plate l2, the surface that is presented to the view in Figures 2 and 3, up thru said interior, thru the core or reel 20 and indirectly thru cover opening I8, with the helically threaded end MA of the spindle disposed outside of the core and of the drum.

Said core or reel, 20, longitudinally regarded,

consists of a main body or strip-corresponding section 2! and an extension 22, also referred to as a selective turning means, which may be detachably or otherwise secured to the main body or section 2 i, or, as shown in Figure 3, may be integral therewith. Body 2| is constituted of a discontinuous outer tube ZIA and an inner tube ZIB inside of and spaced from tube ZlA, a plurality of therebetween intervening webs 23, together with extension 22, connecting the two said tubes to one another. See also Figure 4. The supporting-plate-confronting ends or free edges of webs 23 constitute a plurality of tongues 23A, also referred to as primary position-fixing means and which extend substantially radially. The space between said two tubes is indicated by 24. The reel is provided with the axial recess 26, within which the spindle I4 is accommodated in a manner whereby reel 26 is rendered freely rotatable relatively to the spindle and therefore relatively to plate I2.

Section 2! is adapted to disposal thereof under cover plate l1, inside of the drum. Extension 22 is adapted to extend thru opening it and outside of cover plate ll but underneath inner ring 27A or spider 21, the opening in said inner ring, indicated by 28, being adapted to receive therethru the helically threaded end MA of the spindle, engaged by the thereon screwed wingnut 29.

Upon screwing. wingnut 29 onto the spindle, the spider 21 is caused to press the cover plate I? firmly onto the wall-section [9, thereby helping retain the sanding strips and backing elements, which will again be referred to in this specification.

Formed out of the supporting plate 12 is a plurality of substantially radially extending grooves 29, also referred to as secondary position-fixing means, which are adapted to receive and retain said tongues 23A.

Referring to Figure 4, the inside or retained ends of a plurality of-sending strips 30 have been passed thru and are retained contributively by the respective slots 3|, separating the wall sections of the discontinuous outer wall 21A, the other contributive elements that restrain said ends from withdrawal from outer wall 2 IA being detents or staples 32, which are thicker than the transverse dimension of slots 3|, two of which slots being visible also in Figure 3.

Referring to Figures 1 and 2, disposed in housing i5,is a corresponding plurality of backing elements 33, consisting in this particular drum, of brushes, whose backs 33A are dimensioned to be snugly retained by said housings. Elements 33 are disposed partly outside of and adjacent the marginal sections of the drum, spaced successively therealong, substantially equidistant from axis A. They are readily replaceable when worn out. Each is adapted to resiliently support the outside, free end of a respective one of the sanding strips 39, whose presence is indicated, in the case of Figure 2, by dot-and-dash lines 30A, the two circular dot-and-dash lines 30A indicating the inner and outer margins of the assembly of all the sanding strips that are collectively wound onto the reel. In this particular embodiment there are eight sets of sanding strips and backing elements. However, any desired and convenient number may be employed. The strips 30 are seen issuing thru and from the drum slots 34, which correspond to clockwise rotation of the drum. For counterclockwise rotation, the drum slots 35 would be used instead, and of course the sanding strips would then present their coated, abrading surfaces oppositely. Some of the drum slots are indicated also in Figure 3.

In Figures 1 and 2, the sanding strips are schematically shown in working position with their outside or free ends external to the drum. When said ends have been worn to a smooth state, the wingnut 29-see Figure 3-is partly unscrewed from spindle Hi in order to release the cohesion between the spider, the cover plate, the reel and the groove-corresponding part of the supporting plate, whereby, because of the slight withdrawal of the reel from said part, the grooves 29 disengage the tongues 23A and the reel is then in a position for manual rotation thereof to a sufiicient number of degrees to present fresh, unused ends of the sanding strips externally of the drum, the old, used ends being clipped off. Finding the nearest possible interlocking position for the tongues and the grooves, the wingnut 29 is thereupon screwed tightly onto the spindle and the two position-fixing means are again allowed to function for the purpose indicated. The tongues or primary position-fixing means 23A may be alternatively referred to as a supporting-platecoacting means. The preceding steps can of course be taken as often as is necessary until all of the sanding strips in a reel have been consumed, whereupon the reel may be quickly and easily removed and replaced with a fresh reel already loaded with full-length strips, as distinguished from previous devices in this class wherein the reel or core is asemi-permanent part of the drum and must be reloaded by the user with fresh sanding strips individually, entailing more or less laborious effort and time. My drum need not be partly disassembled to permit replacement of strips, nor need it be opened even for occasional desired withdrawal of the strip ends into the interior of the drum, which may be effected by reversing the steps described. The only occasion for opening the drum is for the replacement of the backing elements, which incidentally may take a form other than that of a brush. 7

Figure 1 presents the strips in unslit form. In practice, they are generally slit, each into many narrow, successively edgewise adjoining strips, not overlying one another.

The various parts may be constructed integral with one another or distinct from one another and thereupon semi-permanently or detachably joined with one another in any desired manner and degree of complexity.

While I have described a practical embodiment of my invention in a more orless detailed manner, I do not desire to be limited thereto in any extent less than that set forth in the claims. On the contrary,- I contemplate all manner of changes within the scope of the claims, including the substitution of equivalent means and parts for those described and illustrated as may be dictated by convenience and circumstances for various applications, all of which changes can and will readily suggest themselves to persons skilled in the art.

I claim:

1. A rotatable sanding device comprising a drum consisting of a back plate adapted to be mounted upon a drive shaft, a removable front plate forming a cover for the drum and a uni formly perforated peripheral wall extending between the front and rear plates, a spindle positioned axially of the drum, a reel journaled for rotation on the spindle and slidably mounted thereon whereby said reel may be both rotated independently andslid axially of said drum, indexing means positioned concentrically with respect to the spindle and adapted to cooperate with complementary indexing means carried by the'reel to hold the reel from independent rotation on the spindle when the reel is slid axially to its locked. position, the reel extending through an axial opening in the front plate, releasable clamping mean exterior to the front plate and adapted to cooperate with the spindle for maintaining said indexing releasable means in engagement to thereby maintain said reel in locked position, a plurality of abrasive strips wound on the reel and extending through the perforations in the peripheral wall of said drum, and said clamping mean being releasable to permit sliding movement of said reel and resulting disengagement ofs'aid cooperating indexing means whereby said reel may be slid axially of the drum from its locked position and then rotated to feed said abrasive strips outwardly of the drum.

' 2. A rotatably sanding device comprising a drum consisting of a back plate adapted to be mounted upon a drive shaft, a removable front plate which serves as a cover for the drum, and a uniformly perforated peripheral wall extending between the front and rear plates and having channel-like housings extended inwardly into the drum adjacent each perforation, a spindle positioned axially of the drum and extending through the cover plate, a reel journaled on the spindle whereby said reel may be rotated independently of said drum and having an extension passing through the cover plate, indexing means formed between the reel and the back plate cooperating with jndexing means formed onthe reel to hold the reel in selected positions of rotation around the spindle, said reel being slidably mounted upon said spindle to produce engagement between said indexing means whereby said reel may be slid axially of said drum to its locked position, and releasable clamping means cooperatively associated with the spindle and reel for holding said indexing means in engagement to thereby maintain said reel in locked position, a plurality of abrasive strips wound upon the reel and extending through the perforations in the peripheral wall of the drum, flexible backing means positioned in each channel for yieldably supporting the ends of the abrasive strips exteriorly of the peripheral wall, said clamping means being releasable to permit sliding movement of said reel and resulting disengagement of said cooperating indexing means whereby said reel may be lid axially of the drum from its locked position and then rotated to feed said abrasive trips outwardly of the drum.

3. A rotatable sanding device comprisin a drum consisting of a back plate adapted to be mounted upon a drive shaft, a removable front plate which serves as a cover for the drum and a uniformly perforated peripheral wall extending between the front and rear plates, the peripheral Wall having channels extending inwardly therefrom within the drum adjacent each of said slots, a spindle positioned axially of the drum, a reel journaled for rotation on the spindle and slidably mounted thereon whereby said reel may be both rotated independently and slid axially of said drum, indexing means formed concentrically within the reel and cooperating with indexing means aflixed to the back plate to hold the reel in one of a plurality of locked indexed positions with respect to the drum, a plurality of.

abrasive strips wound upon the reel and extending through the perforations extending clampin means being releasable to permit slid-c ing movement of said reel and resulting disengagement of said cooperating indexing means whereby said reel may be slid axially of the drumv from its locked position and then rotated to feed said abrasive strips outwardly of the drum.

4. A rotatable sanding drum comprising a back plate, a removable front plate, a uniformly per--- forated peripheral wall between the front and back plates, a spindle aflixed to the back platei and extending axially of said drum, a reel journaled on the spindle and slidably mounted thereon whereby said reel may be rotated independently of said drum and slid axially thereof, indexing means between the reel and back plate normally in engagement for holding the reel in indexed position with relation to the back plate' whereby said reel is prevented fromrotating with respect to said drum, the reel having a part extending through the front plate, fastening means arranged to maintain said indexing means normally engaged, a plurality of abrasive strips wound on the reel and extending through the perforations in the peripheral wall of said drum, said fastening means being releasable to permit sliding movement of said reel and resulting disengagement of said cooperating indexing means whereby said reel may be slid axially of the drum from its locked position and then rotated to feed said abrasive strips outwardly of the drum.

5. In combination with a sanding drum, of a base plate adapted to be mounted upon a drive shaft, a removable front plate serving as a cover for the drum, a uniformly perforated peripheral wall extending between the front and rear plates, the peripheral wall having channel elements extending into the drum adjacent each perforation, a reel mounted within the drum arranged to rotate therein independently of said drum and to move axially with respect to said drum, indexing means between the back plate and the reel for releasably holding the reel from rotation relative to the drum, and releasable means extending through the cover and cooperating with the reel exteriorly of the cover for maintaining said indexing means in engagement to thereby hold the reel in locked indexed position with reference to drum, a plurality of abrasive strips wound upon the reel and extending through the perforations in the peripheral wall of the drum, flexible backing elements for the ends of the abrasive strips, one of which is mounted in each of said channels, said releasable means being releasable to permit disengagement of said indexing means to thereby allow rotary movement of said reel with respect to said drum whereby said reel may be slid axially of the drum from its locked position and then s 6. A rotatable sanding device comprising av drum consisting of a back plate adapted tobe mounted upon a drive shaft, a removable front. plate which serves as a cover for the drum and;

a uniformly perforated peripheral wall extending between the front and back plates, a reel concentrically located with respect to the drum, a spindle secured to the back plate axially of the drum, a reel journaled for rotation upon the spindle and slidably mounted thereon whereby said reel may be both rotated independently and slid axially of said drum, the reel consisting of a central sleeve and an outer cylinder reel section, the reel being plurally slotted longitudinally thereof to receive the inner ends of the plural abrasive strips wound on the reel, indexing means formed between the inner end of the reel and the back plate cooperating with indexing means carried by the back plate for maintaining said reel in locked position with respect to said drum, and releasable means exterior of the front plate and cooperating with the spindle and the reel to hold said cooperating indexing means in engagement, said releasable means being releasable to permit said reel to slide on said spindle to thereby produce disengagement between said indexing means whereby said reel may be slid axially of the drum from its locked position and then rotated to feed said abrasive strips outwardly of the drum.

'7. In a sanding device, a drum member, a reel member mounted within said drum member for both independent rotational movement with respect to saiddrum member and for independent axialimovementi. with respect thereto, releasable. cooperating indexing means between said drum member and reel member normally in engagement' to prevent said independent rotational movement to thereby index said reel member with. respect to aid drum member in a first indexed position, and second releasable meansnormally limiting said independent axial movement of said reel member to thereby simultaneously maintain said releasable indexing means in engagement, said second releasable means being releasable to permit axial movement of said drum. member with respect to said reel member and disengagement of said indexing means wherebysaid reelmember may be moved axially of said drum member and rotated with respect thereto to a second position and indexed inv such second position by reengaging, saidindexing means;

TEOFIL L; BONKOWSKI.

REFERENCES CITED The following references are of record'in the file of this patent:

UNITED STATES PATENTS Edwards Mar. 6, 1934 

